The following information is generally accepted by historians:
1. The Chapel of the Immaculate Conception was founded prior to 1335 by Beatrice d'Este, wife of Galeazzo I, Duke of Milan. The Chapel was attached to the church of S. Francesco Grande, Milan, and was demolished in 1576, at which time the Altarpiece was removed.
2. The Doctrine of the Immaculate Conception, the commissioned subject matter of the altarpiece, was officially recognised by Pope Sixtus IV in 1477.
3. 1479 the Confraternity of the Immaculate Conception contracted Francesco Zavattari and Giorgio della Chiesa to decorate the vault of the chapel.
4. 1480 the Confraternity of the Immaculate Conception contracted Giacomo del Maino to create a large wooden altarpiece with spaces for paintings and with carvings and decoration, to be placed above the altar of the chapel. Final payment was to be made on August 7, 1482.
5. 1483, April 25th, Prior Bartolomeo Scorlione and the Confraternity made a contract with the painters Leonardo da Vinci, Ambrogio de Predis and his brother Evangelista de Predis to provide three painted panels, a relief panel and several smaller panels. The subject of the whole altarpiece related to the doctrine of the Immaculate Conception. The content of each major section was stipulated. The colours of major areas and the use of gold leaf were contracted.
6. There was no contractual determination of which artist was to provide which part of the whole. They were commissioned as equals, except that Leonardo was accorded the title of "Master". However Ambrogio de Predis is known as a painter and it is presumed that Evangelista was the gilder and assistant. Evangelista died in 1491.
7. There was an initial payment of 100 Lire made on May 1, 1483. Thereafter payment of 40 Lire per month was to be made from July 1483 until February 1485 totalling 800 Lire. Another sum of money was to be negotiated upon completion and delivery of the work.
8. 1483, December 8th. The painting was to be finished and installed by the Feast Day of the Immaculate Conception, the same year, giving seven months for its completion.
9. 1490-95, Ambrogio and Leonardo petition the Confraternity stating that they have completed the contracted work but that the centrepiece alone cost the whole 800 Lire and they ask for a further 1,200 Lire, according to the contract. But they were offered only 100 Lire as a result of the petition. Leonardo and Ambrogio then request Lodovico Sforza, the Duke of Milan, to intervene and persuade the Confraternity to pay them or else appoint two experts to represent the various parties, to evaluate the work. If agreement over the payment cannot be met, the painters request permission to withdraw the work itself. NOTE: The painting is in possession of the Confraternity.
10. 1494, Charles VIII of France entered Italy with 25,000 men, stopping at Milan where Ludovico encouraged him to attack Naples. They reached Naples on 22 February 1495 and expelled Alfonso with Charles being crowned King of Naples.
11. 1495, Leonardo painted the Last Supper in the refectory of the Convent of Santa Maria della Grazie in Milan.
12. 1499, Louis XII of France invaded Lombardy. His wife Anne of Brittany gave birth to a daughter a few days later.
13. 1499, Leonardo left Milan
14. 1501, Fra Pietro da Novarella, after a visit to Leonardo in Florence, wrote to Isabella d'Este of Mantua that Leonardo was working on a Madonna for Louis XII's secretary, Robertet and that he had an "obligation" to complete for the King himself.
15. 1503 A further written appeal was made by Ambrogio for settlement. Louis XII wrote to the commander of Milan on March 9, 1503 concerning this appeal and requesting his intervention.
16. 1503, June 23, the Confraternity set out a deed contesting De Predis' request for evaluation of the work or its return. NOTE: The painting is in possession of the Confraternity, not the artists.
17. 1506, De Predis succeeded in re-opening the case and demanding expert valuers to be present, but when the meeting was called on April 4th, one was absent and the case was adjourned.
18. On April 27 1506 an evaluation was made. It was judged that the work was still incomplete. Leonardo was requested to finish it, but he was still absent from Milan.
19. 1507, August 7th. Ambrogio received a payment which with that made in October 1508 equals 200 Lire.
20. 1508, August 18. The painting (which has been further worked on, presumably by Ambrogio) is delivered and put into place. October 23rd 1508, Ambrogio received a final payment. His payment is acknowledged in correspondence by Leonardo who foregoes his share in favour of the De Predis.
21. In 1524 and 1576 The Virgin of the Rocks in the Chapel of the Immaculate Conception was invoked against the plague. [Wasserman p 110]
22. 1625 The Virgin of the Rocks now in the Louvre was seen at Fontainebleau by Cassiano dal Pozzo.
23. 1785, June-July, Gavin Hamilton, a painter, purchased the National Gallery Virgin of the Rocks from Count Cicogna, administrator of Santa Catarina alla Ruota which succeeded the Confraternity of the Immaculate Conception. The Hamilton heirs sold the painting to Lord Lansdown.
24. 1880, The painting passed from the Earl of Suffolk to the National Gallery for 9,000 guineas. It was reported to be in a poor state of preservation and was attributed by some critics to Leonardo and by others to Bernardino Luini.
25. In the past decade, the National Gallery Virgin of the Rocks has undergone conservation and detailed examination including by infrared reflectogram, which revealed traces of an earlier composition beneath the present picture.